Centering-tool.



PATENTED MaJ-,1903.

S. G. TWAMBLEY.. CENTERING TOL.

APPLICATION FILED JUNE 2s. 1902.

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. Y Jlifmgzys TME worm UNITED STATES i PATENT OFFICE.

SAMUEL G. TWAMBLEY, OF BIDDEFORD, MAINE.

oENTERlNc-Too-L.

SPECIFICATION forming part of Letters Patent N o. 724,759, dated April 7, 1903.

Application tiled .Tune 23, 1902. Serial No. 112,868. (No model.)

To all whom, it muy concern.-

Be it known thatI, SAMUELGTWAMBLEY, a citizen of the United States, residing at Biddeford, in the county of York and State of Maine, have invented a new and useful Centering- Tool, of which the following is a specification.

The object of the presentinvention is to provide a simple and convenient tool for accurately centering staffs and arbors in the manufacture or repair of watches.

The tool is designed principally asan aid to watchmakers and jewelers in marking or forming a slight indentation in the exact center ot a broken arbor or staff to form a firm stand for the drill; but it may be employed in the form of a larger tool or apparatus for centering spindles, shafts, or other devices which are to be turned or drilled.

With these and other objects in view the invention consists in the novel construction and arrangement of parts hereinafter described, illustrated in the accompanying drawings, and particularly pointed out in the appended claim.

In the drawings, Figure l is a perspective view of a centering-tool constructed in accordance with my invention. Fig. 2 represents details of portions of the tool detached. Fig.'

3 is a longitudinal sectional elevation of the tool drawn to an enlarged scale. Fig. 4 is an end elevation of the needle or center-marking device.

Similar numerals of reference are employed to indicate corresponding parts throughout the several figures of the drawings.

In the centering of a staff or arbor as practiced in watch repairing at the present time the staff or arbor is mounted in a metallic or cenent chuck, and after facing oi the broken end the center is marked by a graver or similar tool in order that the drill may be correctly entered. This operation is difcult and tedious, and the present invention aims to reduce the time and labor involved by providing a tool which will automatically center the sta or arbor, so that a mark or indentation may be made in the exact center where the drill is to enter.

In the drawings, l designates a guiding-cylinder bored out for the greater portion of its length and adapted for the reception of a sliding rod 2, having a suitable knob or handle 3,

by which the rod may be moved to and fro or turned Within the cylinder. The cylinder is provided at a suitable point intermediate of its length with a handpiece 4., by which the tool may be held np to the work. At one end of the cylinder is a conical opening 5, extending from the extreme end of the cylinder to a shoulder 6,tl1roughwh ich a contracted opening is formed for thepassage of the markingneedle '7, the latter being secured to the end of the'rod 2. The outer end of the needle is pointed in the manner shown in Fig. 4, its end being ground down to form three facets the angular meeting edges of which will form a strong but delicate point which will readily mark or slightly indent the end of the staff or arbor.

In using the device the stad or other device to'be centered is mounted in a chuck with the broken end'outward, and the broken pivot is faced off in the usual manner. The end of the stad or arbor is then entered in the conical opening,"while the tool is held in axial alinement with the statt, the handpiece .4. being held in the left hand, while the knob or handle 3 is held between the thumb and finger of the right hand and pressed inwardly until the pointed end of the needle is in contact with the end of the statt. To make a slight indentation, the lathe-chuck is turned in one direction while the knob 3 and needle are held or slightly turned in the opposite direction. As the needle is fitted accurately in the opening in shoulder 6 and rod 2 ts snugly in the bore of the cylinder, the centering-mark will be made in the exact center of the end of thestaff or arbor without regard to the diameter of the latter, arbors or pivots of small diameter extending much farther into the conical opening than those of larger diameter.

The tool as thus far described is used for centering very small pivots, and for larger work, as where in some cases it may bejnecessary to center from the face of a pinion or a large arbor, I employ an additional centering IOO sired, but are preferably made slightly tapering in order that they may be more rmly held together, and to assist in binding the parts the inner end of the cylinder 9 is slightly split, as indicated at 11.

The outer end of the larger cylinder 9 is provided with a conical centering-opening 12, into which arbors and other devices of comparatively large diameter may be readilyinserted and centered. The conical guidingopening terminates a shoulder 13, in which is formed a guiding-opening for the end of the needle 7, and when the larger cylinder 9 is in use the needle has a support in both cylinders and cannot move from place.

The device may be employed on a larger scale for centering objects of any diameter, and while the construction herein described and illustrated in the accompanying drawings is the preferred form of the device it is obvious that various changes in the form, proportion, size, and minor details of structure may be made Without departing from the spirit or sacrificing any of the advantages of thc invention.

Having thus described the invention, what I claim isl In a device of the class specified, a bored `cylinder having at one end a conical opening for the reception of the device to be centered, a rod mounted in thecylinder-bore and having an operating-knob, a pointed needle carried bysaid rod and adapted to a guidingopening to the rear of the conical opening, a handpiece secured to said cylinder, an auxiliary cylinder having a tapering bore adapted to fit on the correspondingly-shaped portion of the main cylinder, said auxiliary cylinder having a needleguiding opening and being provided with a conical opening of a different size from the conical opening of the bored cylinder for the reception of the device to be centered.

In testimony that I claim the foregoing as my own I have hereto aixed my signature in the presence of two witnesses.

SAMUEL G. 'lWAMBLEY.`

\Vit.nesses:

J. H. J ocHUM, Jr., JNO. E. PARKER. 

